1. Field of the Present Invention
The present invention relates to an apparatus to support patients during medical procedures. More particularly, the present invention is directed to a movable patient support apparatus which has a removable surface that is interchangeable with a variety of configurations each of which are generally constructed of x-ray translucent material.
2. Prior Art
There exists a large variety of patient tables for medical applications, each of which is generally functional within a narrow range of clinical procedures due to its singular table top design as well as its overall configuration. However, in all cases, the table consists of two or three basic elements. Generally there is a table attached to a supporting mechanism and a means to move the table in various directions, including up and down. The moving mechanism may be manually operable or may be power assisted in many directions other than merely up and down. The ability to move the patient, once they are on the table is of importance to clinicians, as well desirable for accessibility to many of today's modern medical diagnostic or therapeutic devices, such as x-ray equipment.
The final configuration of a particular patient support unit is arrived at after contemplation of the various modes and methods available for support and mobility for the types of surgical access required, as well as satisfying the many conflicting clinical requirements.
Support structures for the patient table are generally divided into three types, namely base mounted, end mounted and side mounted. Additionally, a number of combinations or variations may also be constructed.
The base mount configuration is traditionally associated with a standard operating table. It is a support means whereby the table is attached to the support structure directly underneath the table. Examples of a base mounted configuration are described in U.S. Pat. No. 4,387,888, Marinakis; U.S. Pat. No. 4,540,165, Green et al.; U.S. Pat. No. 4,146,793, Bergstrom et al. and U.S. Pat. No. 3,814,414, Chapa.
Advantageously, the base mounted configuration permits unrestricted access at least one end, both sides and the top of the table (of course this is limited at the end having the base). Additionally, the base mount configuration takes up a minimum of floor space, a restricting limitation that must be considered when ascertaining the requirements for a patient support device. While the base mount configuration may be satisfactory for many medical procedures, such a configuration severely limits access from beneath the table as would be required with x-ray equipment imaging through the patients body in the area where the base mount resides.
Accessibility from beneath the table can be improved by having the table cantilevered from the base mount. Such tables are described in publications by SPECTRUM X-RAY CORPORATION and TECNOMED USA. Both tables provide for a floating table top with a reduced base mount section stand. Although accessibility is vastly improved over the traditional base mount configuration, the table becomes exceedingly long (over 9 feet), thus requiring a larger area for the table. Additionally, the cantilevered tables have exhibited tendencies of instability when fully extended.
The side mount configuration improves accessibility to the underside of the table, as well as above the table, both ends and the side opposite the attachment. An example of a side mounted configuration is described in U.S. Pat. No. 3,843,112, McDonald. The table is pivoted to one end of a horizontal arm, the other end of the arm being pivoted adjacent to the top of the pedestal so that the table can be supported outwardly from the pedestal in cantilevered fashion and moved to various adjusted positions. Disadvantageously, such a configuration requires relatively large floor space and restricts access on the side of the attachment and the base mount.
Another example of a side mounted configuration is described in U.S. Pat. No. 3,778,049, Viamonte, Jr. ('049). The patient support in the '049 patent provides for a cradle rather than a flat table, however, the concept of using a side support could be employed with a flat patient table. As in McDonald, the accessibility of the area underneath the table is vastly improved over the base mounted configuration. However, the ability of the clinician or support staff to access the patient on the sides is limited to the side opposite the support mount and both ends. While the side support provides the accessibility required by x-ray equipment and personnel, the design is not conducive to medical applications requiring patient access on either or both sides of the patient.
The third configuration generally used, depending on the clinical application is an end mount table. Although, the end mount configuration allows access to both sides, as well as the top and bottom of the table, one end of the table is inaccessible. For diagnostic or therapeutic purposes, this arrangement may be acceptable. However, for surgery, the anesthesiologist and anesthesia equipment are typically positioned at one end of the table. If the other end of the table were inaccessible due to the support mounting, the medical staff would be restricted in the their movements around the table. This may pose problems in an emergency situation.
Various designs for patient tables and the support structure have been discussed. In addition to the general configuration of the table and its support element, the ideal configuration permits the elevation and tilt of the patient in both the longitudinal plane (positive longitudinal tilt is known as Trendelenberg and negative longitudinal tilt is known as reverse Trendelenberg) and the lateral plane.
Additionally, tables may be designed to "float" the patient relative to the support mount. A floating table is one which moves in a predetermined plane on bearings mounted in a frame which is affixed to the support mount. While floating tables are ideally suited to radiology procedures, such configurations are not deemed acceptable for surgical procedures. Their unacceptability for surgical procedures is result of the patient's tethering to anesthesia equipment or other life support equipment.
For any given clinical procedure, there appears to be an optimum table design. Given specific requirements of accessibility and floor space allotments, no one particular design appears to be suited for all clinical applications. The configuration of the table, including the mounting means, chosen for a particular function is generally a collection of trade-offs made to enable the clinicians to perform their functions and have adequate equipment access, as well as using the minimal amount of floor space.
Other factors that must be considered when configuring a patient support unit is the material used to fabricate the table. To minimize x-ray transmission loss through the table, the table is fabricated from carbon fiber materials. Often, the table will not be flat but will be slightly dished, such that the patient may be made comfortable without the need for thick pads. Although the cost of carbon fiber material is high compared to an equivalent table made from stainless steel or other metals, the ability to image through the table is a controlling factor. However, attaching a carbon fiber table top to the support structure is a difficult task since all the load must be transferred and contact pressures become very high. Most commonly, carbon fiber tables are supported from underneath (i.e. base mounted) eliminating the issue of contact pressure. Tables mounted from the sides or ends, generally have a very high cantilever load and the means of mounting is no longer a trivial matter.
An additional factor to consider for providing for a table configuration is the alternatives of either having a fixed installation, where the table is fixedly mounted to the floor and is not readily moveable or having a mobile table, where the table is moveably moved from room to room as required. Often, clinical procedures will be performed in a room that does not make use of a particular table that is already in the room. One example, is the situation in which a general surgery table is moved out and replaced with an orthopedic fracture table. If the table is mobile, space efficiency is improved. However, the present mobile tables do not have the clinical utility or rigidity of fixedly mounted installations.
In summary, the prior art describes attempts to arrange the various design elements in a relatively effective manner that achieves clinical utility across a narrow range of medical procedures.
For example, a table configured to provide free access to the head and neck area is not optimally configured to perform whole body angiographic procedures. The wide range of clinical procedures requires a wide range of patient table configurations to accommodate them. The wide range of patient table configurations necessarily increases the total floor space allocation required within the hospital since multiple rooms with fixed installations of base units are required. While the mobile table configuration attacks this problem by allowing the table to be used in multiple locations, still, the mobile table, by virtue of its simplicity, cannot provide all the same motion, rigidity, and/or access with x-ray imaging equipment of a fixed installation. Finally, when multiple patients are being moved through a room with a fixed table, the table remains idle while the room is being cleaned and sterilized. This limits the efficient use of the available equipment.
Therefore, what is needed is a single table design that can be optimized for each of the various procedures without limiting the procedure or the use of any required imaging equipment. Ideally, the table design would incorporate the clinical utility and rigidity of a fixedly mounted installation with the space efficiency of a mobile design.
While an x-ray patient support apparatus as described in U.S. Pat. No. 4,912,754, Van Steenburg, ('754) has approached the ideal single table, the apparatus does not provide for interchangeable removeable table tops. The '754 patent describes an x-ray table top moveably supported by a shaft extending from a support mechanism and attached to the end of the table top. While the offset support connection to the table top provides accessibility to both sides, the top and bottom, and both ends, the table is not removeable from the support shaft and therefore cannot be interchanged with a table top of specific clinical design.
Ideally, an appropriate removeable table top mounted to a transport cart would enable multiple the table tops to be fitted onto the table base. Essentially, such a table design would combine the best aspects of both a fixedly mounted installation and a mobile device. Such a design would decrease room preparation time, increase space efficiency and clinical utility. Furthermore, for any fixedly mounted installation, the adaptability of the table that is applicable to a larger variety of clinical procedures would be beneficial to a medical facility, both in efficiency in the use of time, as well as the quality of patient care.
Additionally, the optimal table design would satisfy a sufficient number of clinical requirements at a low enough cost such that the table could be used as an adjunct to more complex fixedly mounted installations.